218 C. D. SMITH AND L. A. COTTON. 



The examination of the crystals from the measurements 

 in the tables show that they belong to the tetragonal 

 system. The scanty development of ditetragonal pyramids 

 and the entire absence of any prism faces renders it some- 

 what doubtful as to which group the crystal belongs. The 

 marked difference in the degree of development of the 

 basal planes suggests that the crystals may be hemimorphic. 

 This unequal development of the basal planes has been 

 recorded both for wulfenite 1 and stolzite. 2 Provisionally, 

 therefore, the crystals have been classed in the pyramidal 

 hemimorphic group. 



The followiug table shows the faces common to the 

 crystals measured, wulfenite and stolzite respectively : — 

 1. Chillagite. 2. Wulfenite. 3. Stolzite. 



T T 



e e 



6 



b b 



P P 



IT 7T 



f 



k 



y 



The forms marked with an asterisk have been recently 

 recorded as new for stolzite. 3 It thus appears that though 

 in their occurrence the crystals are associated with 

 wulfenite, their crystal measurements are more nearly 

 related to stolzite. 



The value of c axis is not intermediate to that of stolzite 

 or wulfenite, but is less than that of either of these minerals. 



1 Charles A. Ingersoll, On Hemimorphic Wulfenite Crystals from 

 New Mexico. Am. Jour. Science, 1894. 



2 Dr. C. Hlawatsch, On Stolzite and a new Mineral Raspite from Broken 

 Hill. Rec. Geol. Surv. N.S.W., 1898, Vol. vi, Part 1, pp. 51-61. 



3 E. Artini, loc. cit. 



013 



r 



Oil 



e 



032 



e 



*113 



b 



111 



P 



133 



77 



*115 



f 



*117 



k 



*119 



y 



